Challenge from last time

Remember...
Suppose you have 9 coins. They are all identical (look, feel, smell,
taste, etc.), except one of them is fake and weighs a little more.
You also have a binary scale. That is, it can only tell if one side is
heavier than the other, but cannot quantify the difference (see
picture below). Using the scale only 2 times, how can you find
the fake coin? Using scale = putting coins on it and seeing which side
is heavier.

Did you get it?

Review

Unix commands - how do I ...

List contents of directory

Change directories

Move a file

Delete a file

Rename a file

Delete a directory

Go to my home directory

Display the current working directory (ie. where you are)

Go up a directory (go to the parent directory)

Make a new directory

Open up a manual page

8 x 8 Queens problem

In chess a queen can move diagonally, horizontally, or vertically.
Furthermore, it can go as far as it wants to in any single move.
The challenge of the 8x8 queens problem is "how can you place 8 queens
on an ordinary chess board so that no queen can hit any other queen in
1 move?". The image on the right is one possible solution

Half of the squares must be white, the other half black.
None of the white squares may share a side with another
white square (normal chess board configuration).

Display the standard pieces on the chessboard in
their initial positions.

Use the img tag to display
images for the chess pieces.

Assume that an
images folder exists in the same directory as the
html code that you're designing. In that directory you
have pawn.png, knight.png, bishop.png, rook.png,
queen.png, king.png

Okay, so making you write HTML for 64 cells is a little
cruel, so just do the 16 cells that represent the initial
placement of the white pieces.

Find 5 solutions to the 8 queens problem and draw them out on paper.
There are a total of 12 correct solutions, where 2 are mirrors or rotations of
another solution. So there are 10 really interesting solutions. You may NOT use
the solution that is expressed in the image at the top of the page.

Send 1 member of your group up to draw your solutions on the board

A challenge for next time

As everyone knows, knights tell the truth all the time, and liars lie
all the time. At least, this is what evenly behaved knights and liars
do.

Less known is that there are also odd knights, who on odd-numbered days
lie all the time. (On even-numbered days, however, they behave evenly,
and tell the truth.) Also, there are odd liars, who on odd-numbered
days, tell the truth about everything, while they lie the rest of the
days.